WR 400- No midrange

I apologize for posting more on jetting. I've searched and cannot find what I'm looking for. This is the situation. I have a '98 400 with the following mods. YZ400 exhaust, YZ timed, airbox lid removed, de-octupussed, taffy mod, grey wire cut. I used Clark's de-octupus guidelines: DVP #4 needle, 180 Main, 48 pilot, 65 start jet, and Pilot Air 100. I live in a pretty low area in Minnesota. The problem is after the taffy mod (which seemed to work really well for eliminating the throttle snap bog) and the de-octopus mod, the bike really loses all power from about 1/4 to 1/2 throttle. The bog from the Pump is gone (thanks Taffy) it really pulls quick but loses all its power in the mid-range, then it picks up again and starts spinning the tires once I'm through teh midrange. I replaced a #82 starter jet with a #65. In clark's memo he says the stock is a 60. Did I grab the wrong one or would that even matter? I played with the fuel screw and the idle but that didn't make a difference. I can get it to idle but the bog will not come out. Should I put the old needle back in (obdt) or should I lower the clip on the DVP? I'm really confused. It didn't really make any sense to me when I found a #82 starter jet when I expected to find a #60 (left side of the Main Jet).

I am no expert on some of the Mods you have but the 180 main & needle are probably the best place to start. try going leaner on the main and 1 or 2 clips up on the needle and re-evaluate. You seem rich to me. :)


If you search under Jetting Qs you will find lots of info. Go back about 2 years. With the YZ pipe you may prefer the E taper needle. Look for posts by "Zamakaze". He has a 98 or 99 WR and YZ. Think his jetting is in his signature. His job is to play with his bikes, copy his jetting and I bet your happy.

Mine runs and starts perfect, thats why I ordered the jets per Clarks guidelines also :). All the past posts recommend alot smaller jets than the 180. I can't seem to stop tinkering and will end up with poor runner.


i haven't been this side for a while as life moves on doesn't it but the most disappointing thing is how easily the good and hard earnt info gets lost. it's Yamakazi and not kamakazi who does a lot of work on these.

for my part if you look at my signature you'll see the jetting i ended up with. basically the piece by clark was written in all good faith at the time by a great bloke who green lanes at the age of 50 and was one of the founders of this site. the write up is from about '99 and is factually correct mechanically but is woefully incorrect jetting wise. all clark did was take the then YZ jetting and fit it in his WR. and we all know about yamahas std jetting!

however i think it's fair to say that when a bloke called james dean and i came along we REALLY got to work. in james case it was analytical and in mine it was experience and hard graft. i did over two hundred back-to-back test runs and ended up-for a little while- converting people to my jetting.

it started with one yank in switzerland and then another and another until we really had it licked. but you couldn't turn your back for one minute because there was always some arsehole who was running a monster pilot jet and a needle the size of a babies arm who swore his bike was brill.

although even the curator of the WR page was converted, actually i think they both were, they have steadfastly refused to archive the legendary 'jetting Qs' thread, abbreviated and in it's A-Z context. my place in TT history is unassured.

so just remember folks, and long after i've gone don't forget- keep reminding people that the Q is a [@#$%&*!] needle and that anything above a 42 PJ 'marks your card' :)

what should have happened if anyone could have been arsed was for a footnote to be added to clark's write up. as it is he has been in the archives mis-jetting bikes ever since!!!

but for the curators to change clark's write up would mean acknowledging the hard work that JD and especially i put in and the next thing they would have to admit is that the success of this site (that's all of TT) was built upon JD and i as well as a couple of others.

and that folks they can't do. it's a sad day when a man has to blow his own trumpet but i don't think they can get away with being so high-browed over it.

for those that don't know, 4 years ago TT was just a WR400 and a YZ400 page. but we tested flywheel weights, IMS tanks, exhausts, jetting, filters, cam timing, big bores, carbon airboxes even ignitions. TT quickly became known as the place to come for a non-bitchy friendly exchange of advice. and then i joined as well and phuqed it up :D :D :D

it's you boys that make the site. keep up the good work.


Good to see you posting wisdom again Taffy! We all appreciate your "Yoda" jetting pressence on this forum. :) I have read most of your archived experience. It seems that Yamakaze and you agree on most things but the pilot jetting circuit. He likes it richer than your settings. You are right about the current state of this forum. Everyone has been very helpful and this forum still does not bring in a lot of trash talk like other forums on the web. The TT members all need to be praised for keeping this a great forum in the spirit of it's founders! :D :D :D

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